- add SMTPD_QUEUE_USER define
- fix wrong error message in mfa.c
- support running the queue as user SMTPD_QUEUE_USER if exists
Merge branch 'master' into issue73-separate-queue-user
fix conflict
Merge branch 'master' into issue73-separate-queue-user

Conflicts:
	smtpd/smtpd.c
Merge branch 'master' into issue73-separate-queue-user
Merge branch 'issue73-separate-queue-user' into monkey
- rename IMSG_QUEUE_DELIVERY_* to IMSG_DELIVERY_*
- consistent naming for pause/resume control messages as IMSG_CTL_PAUSE|RESUME_*
use IMSG_CTL_* for IMSG_SCHEDULER_* control messages.
change IMSG_MDA_SESS_NEW to IMSG_MDA_DELIVER
rename IMSG_BATCH* to IMSG_MTA_BATCH* and tweak names
- rename IMSG_SMTP_ENQUEUE to IMSG_SMTP_ENQUEUE_FD to make it clear it is
  a FD request.
- add a BOUNCE_INJECT message to create a bounce message from a bounce envelope
smtp process needs to cope with temporary failures
warn if authentication table does not exist
wrong message
If we leave the loop with a failure, and no connection, drain again
to flush the tasks.
Implement support for intermediate bounces.  The scheduler can send a
IMSG_QUEUE_BOUNCE message to the queue to trigger an intermediate bounce
for an envelope.  The envelope structure is extended to hold the type of
bounce.
Merge branch 'master' into issue143-auth-temp-fail
avoid NULL deref in mailq
Mark relay as failing if no valid (as in not disabled) MX exists, even
if there are running connections.  Fix a loop in mta_drain() when it
tries to keep creating connections when the previous ones are still
active but have flagged all MXs out.